P0318

DTC P0318

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC P0318
- Rough Road Sensor Circuit




Circuit/System Description

Correct engine misfire detection is dependent on whether or not the vehicle is experiencing a rough road condition. A rough road condition causes unexpected crankshaft fluctuations. In order to detect a rough road condition, the electronic brake control module (EBCM) communicates a wheel speed signal over the serial data circuit to the engine control module (ECM). The wheel speed sensor information allows the ECM to distinguish if the crankshaft speed variations are caused by a rough road condition or are caused by a true misfire.


Conditions for Running the DTC

* The ignition is ON, or the engine is operating.
* DTC P0318 runs continuously once the above conditions are met.



Conditions for Setting the DTC

* The EBCM reports a wheel speed sensor failure to the ECM.
OR
* The ECM does not receive communication of a rough road signal from the EBCM for greater than 5 seconds.



Action Taken When the DTC Sets

DTC P0318 is a Type C DTC.


Conditions for Clearing the MIL/DTC

DTC P0318 is a Type C DTC.


Diagnostic Aids

The following table illustrates the ECM connector locations:






Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify there are no communication DTCs set.

• If there are communication DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) for further diagnosis.

2. Engine idling, observe the scan tool DTC information. DTC P0318 should not set.

• If DTC P0318 sets, refer to Diagnostic Starting Point - Antilock Brake System (Diagnostic Starting Point - Antilock Brake System) for further diagnosis.

3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.